Could you roughly describe your vision of the situation? taking into account the fact that the MC likes to tickle his nerves with the risk of being caught, but does not want to be caught. MC not a stupid.
Not get caught with what? There were already scenes with him playing around with their breasts at the Spa. My "vision" would be a slow progression of jenna doing more and more shoots, while MC praises her "abilities" to make the mom more jealous. Eventually leading to the mom finding out about them having more of a relationship than they know. We've established by the end the Jenna is a sexually deprived horny anal slut who, literally, sped over to his house to get fucked and could think of nothing more than sex while she was doing a porn shoot for the first time on his bed. Jenna already admitted her cheating to her sister, and she's already "told" her sister she knows about what they do in the shoots. Considering what jenna has experienced, it's not out of the realm of possibility that she already assumed, but doubted, that they fucked. At the spa, we were also introduced to the competitive nature between Jenna and Adrianna.
One might argue that, if Jenna is introduced as the catalyst, then MCs grip on her might loosen because she now has a support network. However, Jenna is already dick starved and cheating on her husband, whom never touches her. She'd now has unlimited access to the best dick (her words) she's had if Adrianna was aware. What would she do? Push him away? What would adrianna do? Protest? Then MC pulls the same low quality arguments he did with the Gold Digger to make Adrianna panic into submitting to all this absurdity. She's already fucking her son, why can't her sister do it too? Is a random whore better than her sister?
Hell, it was teased that he wanted a 3some with them. Considering how Far gone the Mom and Jenna is by the end, you could weave a story plotline in there. It obviously won't make much sense, but none of the story makes any real sense anyway... The arguments he uses to "convince" his mom half the time are of low quality.
tl;dr; continue the Jenna corruption and use her as the catalyst the break the mom. Jenna was already broken.
That would be my "vision" for a jenna scenario. However, it could be any of the girls. Just not some random, paid for gold digger with no purpose but the ending...